


Installation

by ThePersonWhoWritesThings



Category: Vocaloid
Genre: Anal Fingering, Anal Gaping, Anal Sex, Awkward Boners, Cum Swallowing, Exhibitionism, F/F, Futa on Female, Futanari, Girl Penis, Name-Calling, Oral Sex, Penis Swap, Spanking, Vaginal Fingering
Language: English
Status: In-Progress
Published: 2015-05-17
Updated: 2015-05-20
Packaged: 2018-03-31 01:39:45
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 4,425
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/3959614
Author URL: https://archiveofourown.org/users/ThePersonWhoWritesThings/pseuds/ThePersonWhoWritesThings
Summary: <blockquote class="userstuff">
              <p>Miku is noticed while staring at Luka, and Luka discovers something rather interesting as she inspects the blue-haired woman more closely.</p>
            </blockquote>





	1. 1

**Author's Note:**

> \- Disclaimer: This fic contains one or more female characters who possess, at some point, both functioning primary sexual characteristics (basically, a penis and vagina). This is what the "futanari" tag is describing. As this cannot be drawn *directly* to a possible human trait (disregarding the fact that the characters are AI/robot singing programs), I see no reason why it should be seen as possibly offensive; however, if there are any qualms, then I kindly ask you to turn away. If you're just not interested in this kind of thing, then I must ask you to turn away too. Otherwise, read on.

Luka felt eyes upon her as she walked through the city. Looking around, she eventually saw none other than Miku, who, upon being seen, quickly shifted her gaze downwards. Her interest piqued, she began walking over to where the blue-haired woman was sitting on the secluded bench shaded by several trees and surrounded by bushes. As she approached, Miku began to grow flustered, crossing her arms above her crotch and attempting to pull down her skirt repeatedly. As Luka reached a close enough distance to see what she was on about, she caught a sight of what she had been trying to cover. Luka's eyebrows rose. The woman's gaze flicked downward, her blue eyes focusing on the other's feeble attempts to hide herself, before moving upwards sharply to meet her eyes.

"Well, Hatsune Miku, I had not anticipated we would meet in such a way..."

Miku, still attempting to hide her raging erection from under her flimsy delicates and skirt, spluttered, trying to act as if nothing was out of the ordinary, "W-What?! I-I mean, what do you mean by that? T-There's nothing odd about the way we've just met now!"

Luka laughed lightly; she found the whole act rather cute. She responded in a cool, suggestive tone, "Miku, I can see what you're trying to cover up there. I wonder, was I the one who made it this excited?"

The blue-haired woman's eyes opened wide, pointed towards Luka's own in tearful fear. She slowly stopped herself from fidgeting with her clothes, placing her shaking arms at her sides and allowing the throbbing bulge to be completely seen. Luka could not stop herself from glancing at it again, with a look reminiscent of hunger crossing her face.

After taking a few deep breaths, Miku responded, "...Y-Yeah. I, um, saw you walking while I was sitting here, and I kinda couldn't look away, and then, u-uh...t-this happened;" she gestured with one hand to her hard-on.

Luka smiled. "Well, Miku. Are you ashamed of yourself? You've created a very awkward scenario for us both," Luka said, feigning annoyance.

Miku tensed up again, becoming anxious. "I-I'm sorry! Y-Yes, I am ashamed, very! I've interrupted your busy schedule with my careless lust..."

Luka could not stop her devilish grin; she loved the look of shame on Miku's face. She had wanted to have some fun with this woman for a while now, and had, before now, only taken chances to regard her features. She was a little shorter than her, with a body that was nice and tight and accentuated in all of the right ways. Perky breasts, a slender body, wide hips, a well-endowed rear. While she hadn't expected _that_ , it was certainly not something she minded; indeed, she decided, after looking around for any others and determining that they were alone, to have a little fun with it.

Approaching the idea with Miku in words, she spoke with a hint of playfulness in her voice, "Miku, I am only kidding. There's nothing to be ashamed about this, and my schedule isn't as busy as you may assume. It is admittedly an odd way to meet up with someone in a semi-public setting, but..." She quickly got on her knees, in front of Miku's closed legs, and reached her hands out to grace her fingers upon the soft skin of Miku's thighs, "...I think I'd like to have some fun with this."

Miku's eyes were wide in disbelief. She began spluttering again, "L-Luka, w-what..?!"

Frowning, Luka decided to quiet her worries, speaking in a slow, lustful tone, "Miku, please. I need you to relax for this." She moved her hands further up Miku's thighs, slowly reaching under her skirt.

Miku closed her eyes and tried to process what was happening. As Luka lifted her skirt away from her legs and hooked her fingers under the elastic of her panties, she began to calm down, spreading her legs apart to give Luka easier access and watching Luka's tantalizing actions with anticipation.

Blue eyes filled with naughtiness met Miku's, and Luka began to slide her panties off. The fabric dragged her erection downward until enough force was applied for the elastic to clear the head; then, it sprung upwards suddenly as it was freed into the open air. Luka slid the panties all the way off, placing them to the side. Then, she fixed her eyes upon what was now exposed to her.

Interestingly enough, it wasn't only a penis that Miku had; under the base of her shaft was her wet vagina, sans her clit; it seemed her penis had replaced that. Luka smirked; she was going to enjoy this. "My, Miku, it seems Master has gotten creative with this lewd installation. Let's see how it feels to give attention to both of them at once..." Luka said.

Before Miku could react to what Luka was suggesting, she gasped sharply as she felt two fingers enter her and a hand grip her shaft, beginning to pump up and down. As Luka began working a rhythm with this setup, Miku's breathing increased, her face burning hotter than before. It felt heavenly, and Miku wondered why she had ever considered this installation a bad thing. She made heated noises as she watched Luka pleasure her, with feelings of disbelief still lingering within her. This had all seemed to happen so quickly.

Luka was getting quite excited as well; the smell of Miku's sticky fluids filled the air, the hormonal scent electrifying her senses. Her eyes fixed on the precum that had begun dripping down her shaft, and as if in a trance, she leaned her head forward. Sticking out her tongue, she lapped up all of the substance going upwards from her shaft to the tip of her penis. It tasted sweet, and she wanted more; so she opened her mouth and slid Miku's cock inside. She began bobbing her head up and down, removing the hand she had used to work her shaft to shift aside her own clothing and rub her wet folds lightly. Luka swirled her tongue around Miku's head and shaft, sampling the precum forming at the tip occasionally.

Meanwhile, Miku's mind had been on overload. There was so much pleasure flooding her senses, and when Luka had begun sucking her dick, it had only spiked higher. Her vision blurred, and her breathing had become more frantic. Gripping the edge of the bench she was on, she figured it wouldn't be very long before she reached her limit.

Now, Luka decided to push things further; bracing herself, she began taking Miku's cock all the way down her throat. It was a slow process, filled with sounds of her own choking, but her lips finally touched Miku's light-blue pubic hair several seconds after she had begun her endeavor. She added a third finger to her lower labors, moving in and out of her more quickly; as for Luka's own masturbation, she now began fingering herself under her clothes.

Miku had responded to Luka's escalation by letting her mouth hang open; shocked, throaty noises had escaped her, and she seemed paralyzed in a kind of ecstatic stupor. Luka now began moving her head up and down slowly, achingly, sounds of gurgling and feeble resistance filling the air. Miku could hear her own heart in her ears, pounding away. It felt so  _fucking_ good, amazingly good; the sensitive touch of Luka's tongue, the wet heat of her mouth, the raw feeling of the inside of her throat. Luka flicked her eyes up to Miku's own as she continued her efforts; a wanton glint lay in the blue. At this, something clicked inside of her, and Miku began to feel the rising intensity in her loins.

She cried out in a raw voice, "L-Luka! I'm gonna  _cum!_ " Luka then moved her head up so that only Miku's head was in her mouth, and began sliding her three fingers in and out of Miku's pussy as fast as she could; she matched this speed with her own, self-directed efforts, and she found that she was near her peak as well. Miku shut her eyes yet again and let her head hang backwards. Her whole world was focused on that upward slope to her orgasm, as it grew nearer and nearer; then she came.

Miku cried out, a high pitched noise that was like a squeal. Her genitals began pulsing, semen shooting out of her penis into Luka's waiting mouth. Her whole body shook and shivered, and was filled with an intense, all-over buzzing. Luka herself attempted to swallow Miku's load as best as she could, and in tasting the hot, bitter cum, she came as well, wincing at the intensity while still keeping up with her task.

Finally, once they had both begun coming down from their highs and Miku's penis had softened, Luka helped Miku back into her panties and they both stood, sweaty and blushing.

Luka spoke first, breaking the silence, "W-Well. How would you like to go back to my apartment? Perhaps you could stay a while..."

Miku blinked, her body facing the stupor of afterglow, and nodded. "Y-Yeah. That'd...uh, that'd be nice."

So they walked in silence together to where Luka lived; Luka unlocked the door and Miku stepped inside. It was a small, cozy living space that smelled of cherry blossoms and made Miku rather sleepy. Luka was drowsy as well, and, to Miku's surprise, she suddenly began stripping off her clothes.

"H-Hey! Don't you think we should wait a while before doing that again?" Miku said, exasperated.

Luka laughed, and responded, "Miku, I'm only taking off my clothes because I sleep in only my underwear. Aren't you in the mood for a nap, too?"

Reassured, Miku spoke, "Y-Yeah, I am. Um...could I take my nap with you?" She cast her gaze downward, suddenly very shy.

_Cute,_ thought Luka, and she again replied in reassurance, "Of course, Miku. I thought that was implied. I have space enough on my bed."

Miku looked back up, and nodded silently in acknowledgment. She took off her clothes, down to her underwear, just as Luka did, and together they walked into Luka's bedroom. The room was cool and quiet, with a soft light spilling out from the single window. They lifted the covers and slid underneath, Miku facing away from Luka as she clung to her body from behind.

Luka slid one hand down to Miku's ass, giving it a firm squeeze; Miku giggled lightly. In a low voice, Luka whispered into Miku's ear, "We're going to have a lot of fun in the next few days." Miku shivered at this, and in thinking about it, her mind wandered off into sleep, Luka following close behind.

 

\--

 

When she awoke a while later, Luka immediately felt as if something was off. Thinking of it while staring into the dimly-lit bedroom, she focused in on a strange sensation between her thighs. Quickly moving a hand to the location, she gasped at what she felt; something hard, pressed against Miku's ass. At the touch, Luka involuntarily pushed her hips forward in raw response.  _Well, this is new,_ thought Luka. She decided to check if the still-sleeping Miku had hers, and after lightly moving her hand between her legs, she felt nothing like what she had felt hours before.  _So Master has decided to switch things up. Well, however perverted they may be, I certainly won't disappoint, and neither, hopefully, will Miku._

____

AN: Well, it seems more sexy shenanigans are in store for Miku and Luka! If you have a suggestion as to where I should take this in the next chapter, then send it forward. Anal, perhaps? Miku returning the favor now that Luka has a penis? Some expansion of Luka's shame kink that I hinted at briefly?


	2. 2

**Summary for the Chapter:**

> Luka finds something interesting about Miku's program, and they both decide to have a little fun with it.

 

Luka kissed roughly along the length of Miku's neck, and the sleeping woman was roused awake by the sensation. Miku's eyes fluttered open to the sight of the empty space past the side of the bed nearest to her, and her body began to register what she was feeling. Miku couldn't help but grin; Luka was getting rather excited. She gasped and let out a small squeak as she felt one of her lover's hands slide up her body, clasping one of her breasts roughly and twisting the sensitive nipple between her finger and thumb. Miku felt the heat between her legs, the wetness beginning to form as Luka's other hand caressed her thighs, teasing at what was surely her true goal. Her nearly-naked body against her own was hot, and just as Miku had decided on turning around to face Luka and return her desires, she noticed something was off.

Miku thought about it; something about the way Luka was moving didn't quite register in her mind. Locating the source of her confusion, she now noticed a rubbing sensation, against her ass, and as she put two and two together, her eyes widened and she spoke in surprise, "L-Luka, you have a dick now?!"

The pink-haired woman replied in a short, heated voice, "Yeah. I woke up a little while ago and it was just there. Yours is gone, by the way."

To confirm her statement, Miku traced her fingers down to her crotch; but Luka had the same idea, and beat her to the punch. Miku moaned as Luka began to rub her fingers above the cloth, against her heat, and she could feel the absence. The feeling was rather foreign, and she had honestly wanted to use it more now that Luka had come along.

"What does Master want from us now? It seems they've taken mine and placed one on you," Miku said.

Luka, again in her hushed, heated tones, replied, "I don't know, and I don't really care. I guess they just wanted to spice things up, and I'm certainly not going to object."

Miku thought about it, but decided not to worry about it too much; plus, she found the idea of being in Luka's previous position interesting. Instead, she focused her attention on the now, turning over to face Luka and planting her lips firmly against hers. They made muffled noises of excitement, and they allowed their hands to explore each others bodies, their slender fingers sliding over warm curves and intricacies. Miku in particular quickly found a grip on Luka's cock; she began pumping along the length as best as she could at the odd angle, and Luka gasped at the sudden sensation. Luka, on the other hand, became more curious. She slid a hand under the backside of Miku's panties, savoring the feeling of the soft, squeezable flesh of her ass. Her fingers felt between her buttocks, and as Miku flinched at Luka's strange advances, Luka felt something odd. Pressing her finger in, the area gave way, and she now found with a slight start that she had entered some kind of hole on Miku's body. Flinching again, and with more intensity, Miku spoke in a startled tone, "L-Luka, I-I don't think that's meant for what we're doing..!"

Luka furrowed her brows, and replied, "But I can put my finger in there, and it's close enough to everything else. What is this, anyways?" She attempted to wiggle her finger deeper inside, and Miku started to squirm; but Luka found the task difficult, as the hole was very tight.

Miku answered in an anxious voice, "Um...I-I think the people who are a part of Master's race use it to expel waste, which is why I don't think it's supposed to be used for these kinds of activities..."

Confused by this answer, Luka spoke, "But we don't need something like that if we don't require what Master's race calls 'eating' and 'digestion' to survive. Perhaps it is another one of their lewd installations?"

"Well...you're right. Since we're programs, we can't use this..." she presently scanned her files, coming to the name of the specific installation, "...'anus' in the same way that Master's race does. And maybe they do find sexual pleasure with it in some way," Miku mused.

"Then Master must have installed this hole onto you for us to experiment with. Do you want to try something?" Luka asked, her voice laced with interest as the idea began to grow on her.

Miku felt a surge of naughtiness fly through her stomach, and after shyly considering it for a few moments, she nodded to Luka. But she was suddenly unsure again, needing a question answered, "H-How should I...uh...position myself?"

Thinking about it for a few moments, Luka came to an answer, "Get on your hands and knees, and face your ass out towards me."

Giving a light laugh to this, Miku responded in mock offense, " _Well_ , Luka. You're awfully forward about your views of me, it seems. I'm just your bitch, aren't I?"

Luka took Miku's jest in all seriousness, words flying out of her mouth, "N-No, that's not what I meant! I-It just seemed like a good position-"

Interrupting, Miku tried to calm her lover, "Hey, hey, I was just messing with you. I don't mind. And well, I..." her voice grew lower, more wanton, "...I want to be your bitch, anyways."

Not imagining she could grow any harder, Luka now felt, at these words, that she had. They now slipped out from under the covers silently, their eyes, filled with desire, meeting and communicating a silent message of anticipation. Their hair was messy and matted, but they simply moved it out of their faces and continued with their actions. Balancing on their knees and keeping their bodies straight, they slipped out of their panties, shifting their legs around awkwardly; then they were both completely naked. Both of them on their knees again, Miku shuffled over so that she was facing away from Luka, who was now just behind her.

Miku leaned her body against her lover's, turning her head to face Luka and kissing her lips again; a wandering hand found a grip on Luka's shaft and began pumping slowly, lazily. "Just be careful, okay, Luka?" she cautioned her. Luka nodded, and Miku let go of Luka's cock, assuming the suggested position. Luka then moved closer behind, so that her penis was pressed against Miku's ass at an angle between Miku's buttocks.

Luka moved her hips back, so that her penis straightened out; then, she stretched Miku's cheeks apart, locating the hole she had previously found. Taking a hand away from Miku's ass to line herself up with it, she then began pushing in slowly. Tension was shared between both of them as Luka's hips came forward inch by inch. But just as her head began to push inward, the tightness beginning to envelop it, something felt wrong.

"U-Uh, Luka, I think it's gonna be too tight..." Miku spoke, nervously.

Luka felt likewise, and she reversed her actions, again assuming her original position with her cock against Miku's rear. "I think we need something to help facilitate this process..." Luka thought aloud.

Almost immediately, Luka felt that she had realized something new. Blinking, she flexed her fingers in front of her eyes, and soon found that at the thought of Miku's anus, a watery substance began oozing from her fingers. She informed Miku of this, "H-Hey, Miku! Master has installed something in my program just now that I think will be helpful. It's called...'anal lubricant'?"

Miku was elated at this, and said, "Oh, good, you have something that can be used to make this easier! So, I guess Master's race calls this type of sex 'anal'. So...how do you...?"

Before Miku could finish, she was startled by Luka suddenly wiggling her lube-covered fingers into Miku's anus. She finished her thought, a little squeamish at the feeling of the liquid, "O-Oh...um, so it comes from your fingers. T-That's helpful."

Luka spread her fingers out, stretching against the tightness inside of the hole and distributing the lube. She had put two fingers inside initially, and now she added another one; Miku shivered visibly. Now finding a kind of rhythm with her fingers, she began fingering Miku's anus. To her surprise, Miku found that the strange feeling began to morph into one of odd pleasure, and she gave a low moan in response to this confusing sensation. A surge of intense pleasure went through Luka upon hearing this. Suddenly impatient, she removed her sticky fingers from inside of Miku's anus and, after applying some of the substance to her penis, angled herself so that she was at the entrance yet again.

Breathing heavy and hot, Luka warned Miku, "H-Hey, I'm gonna try to go in again."

Miku bit her lip, now knowing for sure that she wanted this, and replied, "Y-Yeah...go ahead. I'm ready."

Luka began the slow process of inching her hips forward yet again, and to the surprise of both parties, Luka's head slid inside of Miku's anus fairly quickly. Luka gasped at how tight it was even with the help of the lube, and Miku gave a short cry at the foreign feeling, not yet accustomed to it. "L-Luka, keep going, I'm okay..." Miku said, encouraging Luka.

Ever so slowly, in equal parts concern over how Miku was feeling and concern over her reaching her orgasm too early, Luka slid more of herself inside. As she came to the point where half of her shaft was inside, she began to feel the wonderful twitching and pulsing caressing her penis, and Luka grunted. She pressed on, going in more and more; and then she could go no further.

All the while, Miku had been taking the experience silently, her breathing fast and hot. She spoke now, her voice spluttering and shaky, "L-Luka, a-are you all the way in..?"

Luka grit her teeth and shut her eyes, and said in a filtered voice, "Yeah!"

Miku allowed herself to breathe for a few moments, and then spoke again, "It...it feels so strange...but somehow I think I like it..."

Opening her eyes and taking a deep breath, Luka braced herself and began to slide out, significantly faster than the speed at which she had entered. Miku gasped at the movement, and Luka steeled herself against the stimulating muscle reactions. Stopping before her head came out, she moved in again, at a moderate pace. Out again, in again, at the same pace. Luka was soon able to work with this pattern without risking going over the edge, and she began to fuck Miku.

Meanwhile, Miku had lost control of her arms, instead allowing her face to meet with the sheets and her arms to relax. With each of Luka's thrusts, with each rhythmic filling and unfilling, she let out a moan, cut off by the next repetition. It was clear now that Miku enjoyed anal sex; to her, although the feeling was rather unfamiliar, she found a kind of enjoyment in how Luka's penis stretched her on the inside. It stimulated her in a way that was like regular sex, and she was equally as wet and hot.

Luka picked up her pace, her hips beginning to meet with Miku's body with a satisfying smack. Her body was on fire, and her vision was hazy and flooded with fog. Dirty thoughts ran rampant through her mind, and in her present condition, she couldn't help but voice some of them. Giving a short, low chuckle, she spoke loud enough so that Miku could hear, "Y-You're fuckin' loving this. You really are a naughty bitch, aren't you? Give me an answer."

Miku let out a cry of pleasure, and she answered obediently, almost yelling in her passion, "Y-Yes! I-I'm...I'm a naughty bitch!"

Smirking, Luka continued, "Are you my bitch, Miku?"

Groaning, she said, "Y-Yes, I am! Luka, I'm your bitch!"

Luka was going faster and faster, ignoring her physical condition. She watched Miku's ass ripple with the impact of her own body, and she raised her arm, bringing her hand down upon the flesh harshly. Miku flinched and grunted at the sudden pain, and Luka cried out again, her voice becoming more and more broken by her hot breaths, "D-Do you like it, slut? Do you like it when I smack your ass while I'm fucking you anally?"

Miku gripped the sheets, overcome by pleasure and nearing her peak, "Y-Yeah! Luka, f-fuck, _please_ , don't ever fucking stop!"

Luka smacked her ass again, and again, as she slammed in and out of Miku, and at every stroke of her arm, Miku's grip on the sheets grew tighter and she grunted between her moans.

As her mind began to fade as she came closer and close to orgasm, Luka gave another throaty word with a smirk, "I-I'm...gonna blow inside, bitch! Gonna...gonna fill you up with my..." Luka's words began to fail her. She was now going as fast as she could, in and out and in and out of that wonderful twitching vice, and she continued on until she reached the climax of her pleasure; then Luka came.

She gave one last thrust, bottoming out inside of Miku once more. She threw her head back as her penis and vagina began to pulse and the waves of euphoria began to tear at her mind. The world seemed to stop; everything in her body tensed up and was electrified. Semen flooded out of her penis into Miku, and Miku, facing the afterglow of her own orgasm that she had experienced some time before, let out an exhausted groan at the feeling of the warm liquid filling her.

Luka's high began to die down several seconds later, and she joined Miku in her post-orgasmic state. She rapidly began to soften inside of Miku, and so she unceremoniously moved her hips back; immediately, semen began oozing out of Miku's stretched out anus, the stream moving over her wet pussy and dripping down onto the sheets.

They were both breathing heavily, their faces red. Shakily, Miku straightened herself up on her knees again, but soon found keeping balance difficult. Catching her as she fell, Luka chuckled awkwardly, and they both agreed with a moment of eye contact that they should lie down and rest. Not bothering to get under the covers or even move after they flopped down onto the mattress, they quickly fell into a sleep, their sleeping bodies haphazard and in disarray.

 

_____

 

AN: Again, as before, suggestions would be great! Criticism is also welcome, as long as you're constructive.


End file.
